1. Field of the Invention
The present invention relates to a vehicle wheel which reduces a noise emission accompanying an air column resonance (cavernous resonance) inside an air chamber of a tire.
2. Description of Related Art
In general, it is known that an air column resonance generated in an air chamber of a tire (hereinafter, referred to as tire air chamber) causes a road noise of a vehicle. The air column resonance is a phenomenon which generates a resonant sound in such a manner that an air in the tire air chamber is vibrated due to random vibrations transmitted from a road surface to the tire, and as a result, a resonant phenomenon occurs at around an air column resonance frequency of the tire air chamber.
Hitherto, a vehicle wheel described in Japanese Patent Laid-open Publication No. 2004-90669 has been known as the vehicle wheel which reduces the noises accompanying the air column resonance. The vehicle wheel includes a plurality of additional air chambers along a circumferential direction of a rim. For more details, in the vehicle wheel, a circular space portion formed between a circular vertical wall which is vertically disposed at a well portion extending in the circumferential direction of the rim and a rising side wall of the well portion toward a bead seat portion side is covered with a cap member. Then, the circular space portion zoned by the cap member, the well portion, and the vertical wall is partitioned by a plurality of separators which are disposed at predetermined intervals in the circumferential direction to form each of the additional air chambers. In addition, the tire air chamber and each of the additional air chambers are communicated with each other through a communication hole formed in the cap member. According to the vehicle wheel described above, the communication hole and additional air chamber constitute a Helmholtz resonator and the air column resonance sound in the tire air chamber can be reduced.
However, the vehicle wheel described above has not a practical structure. That is, it has been necessary to accurately joint a plurality of separators and cap member by welding, bonding, fitting, and fastening, while keeping airtightness to the vehicle wheel where the vertical wall rising from the well portion is formed. Therefore, a mass production of the vehicle wheel has been unsuitable considering securing of the airtightness, a manufacturing manpower, and an increase in the manufacturing cost.
It is, therefore, an object of the present invention to provide a vehicle wheel which can improve mass productivity of the vehicle wheel.